1. Field of the Invention
The present invention relates to a robot controller for moving a robot based on a force applied to the robot, and relates to a robot system including the robot and the robot controller.
2. Description of the Related Art
As an operation method for moving a robot by applying a force to the robot, or a method for moving a robot by applying a force to the robot so as to teach a position, direct teaching is well known. In direct teaching, by directly guiding the robot by applying a force to the robot in a desired direction of movement, the robot can be moved to a desired position and/or orientation on an orthogonal coordinate system.
As relevant prior art documents, JP S56-085106 A discloses a method for moving the position and orientation of a front end of a robot arm, based on a signal generated by a force detector when a manual operation part attached to the front end of the robot arm is operated.
Further, JP H06-250728 A discloses a direct teaching device for a robot, wherein a force sensor arranged on the robot detects a force applied by a human to an end effector, and a robot arm is guided only in a direction determined by an operation direction setting means, when the motion of the robot arm is to be controlled based on a force signal obtained by the force sensor.
In the method of JP S56-085106 A, the position and/or orientation of the front end of the robot on the orthogonal coordinate system are moved in response to the force. However, in this method each axis cannot be moved to a desired position during the direct teaching.
In the device of JP H06-250728 A, when the robot is moved by direct teaching, the direction of movement of the robot is limited so as to move the robot only in the limited direction, and therefore operability of the robot may be improved. The limited direction relates to a direction regarding the position or orientation of the front end of the robot on a Cartesian coordinate system. Therefore, JP H06-250728 A does not describe a method regarding limiting an axis to be driven, wherein each axis is controlled so that only a desired axis is moved, etc.